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FLUORINE

(L. and F. fluere, flow, or flux)

F  at. wt. 18.9984
   at. no. 9
   f.p. -219.627°C (1 atm.)
   b.p. - 188.14°C 
   density 1.696 g/l (0°C, 1 atm.)
   sp. gr. of liquid 1.108 at b.p. 
   valence 1.
Electronic configuration
 SHELL  K L M N O P Q
 SUB  SHELL He Neon Argon Krypton Xenon Radon Eka-radon
1s 2s 2p 3s 3p 3d 4s 4p 4d 5s 5p 4f 5d 6s 6p 5f 6d 7s 7p
Fluorine 1s22s22p5          
Symbol 2P3/2
Fluorine. In 1529, Georgius Agricola des- cribed the use of fluorspar as a flux; and as early as 1670 Schwandhard found that glass was etched when exposed -to fluorspar treated with acid. Scheele and many later jn- vestigators, including Davy, - Gay-Lussac, Lavoisier, and Thenard, experimented with hydrofluoric acid, some experi- ments endhig in tragedy. The element was finally isolated in 1886 by Moisson after nearly 74 years of continuous effort. Fluorine occurs chiefly in fluorspar (CaF2) and cryolite (Na2AlF6), but is rather widely distributed in other minerals. It is a member of the halogen famfly of elements, and obtained by electrolyzing a solution of potassium hydrogen fluoride in anhydrous hydrogen fluoride in-a vessel of metal or transparent quprspar. Modern commercial production methods are essentially variations on the. procedures first used by Moisson. Fluorine is the most electronegative and reactive of all elements. It is a pale yellow, corrosive gas, which reacts with practically all organic and inorganic sub-. stances. Finely divided metals, glass, ceramics, carbon, and even water burn in fluorine with. a bright flame, Until World War II, there was no commercial production, of elemental fluorine. The atom-bomh project and nuclear energy applications, however, made it necessary to produce large quantities. Safe handling techniques have now Ieeen developed and it is possible at present to transport liquid fluorine by the ton. Fluorine and its compounds are used in producing uranium (from the hexafluoride) and more than 100 commercial fluorochemicals, including many well-known high-temperature plastics. Hydrofluoric acid is extensively used for etching the glass of light bulbs, etc. Fluorochloro hydrocarbons are extensively 'used in air conditioning and refrigeration. It has been suggested that fluorine can be su~ stituted for hydrogen - whetever it occurs in organic -com- pounds, which - could lead to an astronomical number of new fluorine compounds. The presence of fluorine as a soluble fluoride in drinking water to the extent of 2 ppm may cause mottled enamel in teeth, when. used by children acquiring permanent teeth; in smaller amounts, however, fluorides are said to be beneficial and used in water supplies to prevent dental cavities. Elemental fluorine is being studied' as a rocket propellant as it has an exceptionally high s-ic impulse value. Compounds of fluorine with rare gases have now been confirmed. Fluorides of xenon, radon, and kryp- ton are among those reported. Elemental fluorine and the fluoride ion are highly toxic. The free element has a charac- teristic pungent odor, detectable in concentrations as low as 20 parts per billion, which is below the safe working level. The recommended maximum allowable concentration for a daily 8-hr. exposure is 0.1 ppm.

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